The Arup Journal Issue 1 2020

The Arup Journal Issue 1 2020
Issue 1 2020

The Arup Journal
The Arup Journal Issue 1 2020
                            4    Cityringen Metro, Copenhagen,
                                 An expansion to the Danish capital’s metro
                                 system using passenger-centred design
                                 Tony Evans, Katrine Falbe-Hansen, Neil
                                 Martini, Nille Juul-Sorensen, Mohammad
                                 Tabarra, Kristian Winther

                            16 Claridge’s Hotel, London, UK
                                 A luxury hotel gains five new storeys
                                 underground, with no disruption to guests
                                 Alice Blair, Sarah Glover, Dinesh Patel,
                                 Andy Pye

                            24 Beijing Daxing International Airport,
                               Beijing, China
                                 Passenger experience and fire safety are at
                                 the heart of this busy airport
                                 Robert Feteanu, Ming Li, Fangzhou Su,
                                 Kelvin Wong, Vala Yu

                            30 Samuel De Champlain
                               Bridge Corridor Project,
                               Montreal, Canada
                                 A novel design and procurement
                                 process was used to deliver this critical
                                 infrastructure project
                                 Douglas Balmer, Jo Balmer, Matt Carter

                            38 Guoco Tower, Singapore
                                 Constructing two geometrically
                                 complex towers as part of a vibrant
                                 new development in Singapore
                                 Dion Anandityo, Jason Tan

                            44 Macallan Distillery, Scotland, UK
                                 A working distillery and visitor
                                 centre that blends in with and respects
                                 the local environment
                                 Jim Deegan, Susan Deeny, Paul Edwards,
                                 Adam Jaworski, Stuart Jordan, Bob Lang,
                                 Alistair Murray

    Beijing Daxing International Airport, Beijing, China:
    Hufton + Crow

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                                                 The Cityringen metro line, consisting of          (JV) partners COWI and SYSTRA to act as            fire and life safety, lighting and construction
                                                 16km of twin-bore tunnels and 17 new              multidisciplinary technical adviser for this       planning. During the design and construction
                                                 underground stations, provides a                  design and build contract. It was the city’s       phase, the JV team acted as Metroselskabet’s
                                                 24-minute loop around Copenhagen’s city           largest construction project in more than 400      technical adviser, assisting the company
                                                 centre, interchanging with the existing           years. Working on the design and procurement       with the tender evaluation, detailed design
                                                 metro, mainline services and buses.               strategy for the contract, the JV provided         check, testing and commissioning, and
                                                 Cityringen runs 24/7 and seeks to                 engineering, architectural and advisory            construction management.
                                                 encourage residents out of their cars and         services, including civil and structural design,
                                                 onto an environmentally friendly form of          risk assessment, cost estimates, and project       Arup led the architectural design for all
                                                 transit. It is a key part of the city’s plan to   and programme management. Arup was also            stages of the project, taking a user-centric
                                                 become carbon neutral by 2025. Cityringen         responsible for the reference design safety        approach at every step. This has resulted in
                                                 opened in September 2019; 85% of                  case on the project.                               spacious, light-filled stations with distinctive
                                                 Copenhagen residents are now less than a                                                             internal façades that echo the locality above
                                                 10-minute walk from a train station.              For the concept and reference design,              the stations.
                                                                                                   Arup (as part of the JV) provided a range
                                                 In 2007, Metroselskabet, Copenhagen’s metro       of services, including geotechnics, structural     Passenger-centred design
                                                 company, appointed Arup with joint venture        engineering, tunnelling, tunnel ventilation,       The original Copenhagen metro lines
                                                                                                                                                      opened between 2002 and 2007 and were
                                                                                                                                                      successful from the start. Building on this,
                                                                                                                                                      the JV’s design for Cityringen focused on
                                                       Cityringen                                                                                     enhancing the traveller experience by

                                                                                                                                                      putting the emphasis on passenger comfort
                                                       Metro lines 1 and 2
                                                                                                                                                      throughout the journey. The metro is a fully
                                                                                                                                                      automated, high-frequency, driverless
                                                                                                                                                      system. The stations do not have ticket

the metro
                                                                                                                                                      barriers, and staff are available on
                                                                                                                                                      concourses, platforms and trains to assist
                                                                                                                                                      customers during their journey. Every

                                                                                                                                                      station has two lifts that take passengers
                                                                                                                                                      from the platform directly to street level,
                                                                                                                                                      making the metro fully accessible for all.

                                                                                                                                                      Tunnel depth has been minimised at station
                                                                                                                                                      locations, thereby reducing passengers’

Copenhagen’s Cityringen metro
                                                                                                                                                      1: The Cityringen line,
line expands the city’s existing                                                                                                                      which opened in
                                                                                                                                                      September 2019, aims
award-winning underground                                                                                                                             to encourage more
                                                                                                                                                      citizens to use this
system, making it even easier                                                                                                                         environmentally friendly
to travel around the capital                                                                                                                          form of transport
                                                                                                                                                      2: Cityringen
Authors Tony Evans, Katrine Falbe-                                                                                                                    (represented on the
                                                                                                                                                      map by a yellow line)
Hansen, Neil Martini, Nille Juul-                                                                                                                     adds a third line to
Sorensen, Mohammad Tabarra
                                                                                                                                                      extremely popular
and Kristian Winther                                                                                                                                  existing metro system
                                          1.     2.

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                                                   3: The stations have                          3: The stations have been designed to be
                                                   been designed to be                           relatively shallow in depth where possible,
                                                   shallow in depth,                             giving clear sight lines between street and
                                                   giving clear sight lines                      platform level
                                                   between street and                            4 & 5: Each station’s surroundings have
                                                   platform level                                influenced their design. At Marmorkirken
                                                   4: Each station’s                             Station, the limestone cladding is a nod to the
                                                   surroundings have                             marble church above
                                                   influenced their
                                                   design. At
                                                   Marmorkirken Station,
                                                   the limestone
                                                   cladding is a nod to
                                                   the marble church
                                                   above                                         For example, in Marmorkirken Station the
                                                                                                 fossil-embedded, sand-coloured Swedish
                                                                                                 limestone cladding is a reference to the
                                                                                                 19th-century marble church above. In
                                                                                                 Trianglen, mirrored glass panels have been
                                                                                                 used to reflect and multiply the colours worn
                                                                                                 by sports fans flocking to the adjacent
                                                                                                 national stadium, contributing to the lively
                                                                                                 pre-game atmosphere. Grey and yellow
                                                                                                 bricks are used in Nørrebros Runddel to
3.                                                                                               complement the yellow brick wall around           6.                                               7.
                                                                                                 the churchyard located above the station.
travel time on escalators and lifts. As            security and physical comfort, while also                                                       Modular design                                   developed further, with the skylights also              6: A 5.5m module is used for
commuters enter the majority of the stations,      optimising passenger flows.                   Cityringen interchanges with the existing         The architectural approach across all 17         acting as emergency air vents, thereby                  finishes to match the module of
the shallow depth helps them to see all the                                                      M1 and M2 metro lines at two locations            stations was to use a ‘kit-of-parts’ design.     reducing the reliance on mechanical smoke               the passenger screen doors on
way down to platform level; and, conversely,       Station identity                              (Kongens Nytorv Station and Frederiksberg         This led to a cost-effective, rational design    ventilation systems and the need for further            each platform
at platform level they can see the exit above.     By incorporating ideas and motifs inspired    Station) and the commuter/regional train at       and modular construction system. Future-         in-station equipment rooms.                             7: Skylights provide natural
These clear lines of sight help people to          by each station’s surroundings, Arup’s        three locations (København H/Copenhagen           proofing the stations was an important design                                                            light at platform level
easily navigate through the metro. Based on        architectural design approach – using         Central Station, Østerport Station and            driver for Arup’s materials and lighting         The lighting design is fully integrated with            8: The skylights’ distinctive
extensive pedestrian modelling work, Arup          sculptural wall panels and cladding on the    Nørrebro Station). Grey natural stone was         specialists. They sought high-quality            the architecture and uses the feature                   glass pyramids appear
developed the concept for station layouts, the     internal façades – draws each                 chosen for both Kongens Nytorv and                long-life fittings and durable self-finished     ‘origami ceilings’ as reflectors,                       throughout Copenhagen
new line’s visual identity and signage for         neighbourhood’s identity into each station,   Frederiksberg Stations, as grey cladding is       surfaces, such as terracotta tiles and granite   complemented by bespoke LED lighting that
effective wayfinding. Static signs are             making the metro a natural continuation of    used inside the existing metro stations, while    platforms, to provide high-impact solutions      helps avoid glare. The origami geometry
combined with dynamic displays and                 the surrounding area. It also helps with      red ceramic panels are used at the three rail     with low maintenance costs.                      was designed using 3D simulations and 1:1
interactive travel panels to generate a sense of   inferred wayfinding.                          transit stations, as the urban trains are red.                                                     mock-up testing of luminaires and
                                                                                                                                                   Where possible, fittings and finishes, such as
                                                                                                                                                   the wall cladding, were specified in 5.5m
                                                                                                                                                   modules. This matches the module of the
                                                                                                                                                   passenger screen doors used on each
                                                                                                                                                   platform to separate passengers from the
                                                                                                                                                   tracks, with the repetition of this module at
                                                                                                                                                   all stations reinforcing the identity of the
                                                                                                                                                   new metro line.

                                                                                                                                                   Bringing light underground
                                                                                                                                                   Metro passengers can navigate from the
                                                                                                                                                   street to the platform without feeling as
                                                                                                                                                   though they are venturing underground. To
                                                                                                                                                   achieve this, most of the 17 new stations
                                                                                                                                                   feature skylights. These provide bright
                                                                                                                                                   natural daylight at platform level, to help
                                                                                                                                                   bring the outside in and improve energy
                                                                                                                                                   efficiency within each station.

                                                                                                                                                   For the first phase of Copenhagen’s metro,
                                                                                                                                                   completed in 2002, Arup contributed to the
                                                                                                                                                   design of the distinctive glass pyramids and
                                                                                                                                                   skylights. For Cityringen, this was
4.                                                                                               5.                                                                                                 8.

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                                      9: The ‘origami ceilings’ act    architectural finishes. A detailed 1:25 scale                                                                                                     of the residual train-induced piston airflow
                                      as reflectors for the daylight   architectural station model was created in                                                                                                        and is always in the direction of train travel.
                                      spilling in from the skylights   which the intensity of the daylight could be                                                                                                      This was made possible by the short (39m)
                                      10: To minimise disruption,      tested in relation to the station space.                                                                                                          three-car trains used on the line – for short
                                      stations were built                                                                                                                                                                trains, the passenger risk exposure and
                                      underneath pre-existing          Design integration                                                                                                                                therefore the emergency ventilation
                                      parks and squares where          Each station has an approximate footprint                                                                                                         direction is far less dependent on the
                                      possible                         of 64m x 20m and a 45m platform length.                                                                                                           location of fire on a train. The fully
                                      11: Four TBMs had to             In order to minimise their impact on traffic,                                                                                                     automatic, driverless system allows fast
                                      tunnel through challenging       utilities and properties during construction,                                                                                                     reaction times, with minimum human
                                      ground when constructing         stations were placed under existing parks                                                                                                         interaction required during emergencies.
                                                                       and squares wherever possible. This has
                                      12: Arup used advanced           allowed new landscaped plazas to be                                                                                                               A mode table of all possible ‘what if’
                                      modelling techniques to          created above many stations, providing                                                                                                            scenarios, assisted by heat and smoke
                                      analyse fire and smoke
                                                                       civic spaces for the surrounding community                                                                                                        sensors in the tunnels and on board the
                                      behaviour in the stations
                                      and tunnels
                                                                       and simple, welcoming entrances and                                                                                                               trains, guides the control centre operator
                                                                       forecourts for passengers.                                                                                                                        to arrive at the correct emergency
                                                                                                                                                                                                                         response swiftly.
                                                                       The compact, driverless metro trains
                                                                       allowed the JV team of engineers, designers                                                                                                       Construction
                                                                       and transport consultants to design smaller                                                                                                       A major metro extension represents long-
                                                                       platforms, helping to shrink the overall                                                                                                          term disruption to any city, but Arup’s
                                                                       footprint of the stations. This meant                                                                                                             careful programme management, together
9.                                                                                                                                                                                                                       with Metroselskabet’s intensive stakeholder
                                                                                                                                                                                                                         management, ensured shopowners, residents
                                                                                                                       11.                                                                                               and visitors could go about their daily lives
                                                                                                                                                                                                                         with minimum disruption during the eight
                                                                                                                       demolition was kept to a minimum, with just       more likely, rubbish-bin fire scenario          years of construction.
                                                                                                                       two buildings demolished for the new metro        replaced the more traditional, and larger,
                                                                                                                       line. The life of the city was able to continue   baggage fire scenario in the design of          Embedding 17 new stations within a
                                                                                                                       fairly undisrupted throughout construction.       station ventilation systems.                    historical city was a delicate engineering
                                                                                                                                                                                                                         design task. It was critical that the impact on
                                                                                                                       Ventilation                                       A simple emergency tunnel ventilation and       heritage structures was minimised. At
                                                                                                                       Arup’s work on the fire and life safety risk      evacuation strategy was adopted, where the      Marmorkirken, the station is 36m below
                                                                                                                       strategy and the tunnel ventilation during the    default ventilation direction takes advantage   ground and is carefully located in a narrow
                                                                                                                       concept design phase helped to reduce the
                                                                                                                       number of intermediate escape shafts from
                                                                                                                       17 to three, significantly improving the
                                                                                                                       visual and physical impact on the city, as
                                                                                                                       well as reducing costs and disruption due
                                                                                                                       to construction.

                                                                                                                       The ventilation design consisted of a single
                                                                                                                       tunnel ventilation fan plant and single-
                                                                                                                       pressure draft relief shafts at each station.
                                                                                                                       The modular station design continued with
                                                                                                                       the civil coordination of over-track
                                                                                                                       ventilation ducts with the station structure.
                                                                                                                       This was repeated along the metro line,
                                                                                                                       where a single tunnel opening and multiple
                                                                                                                       grille over-track openings were connected
                                                                                                                       to the single ventilation plant via dampers.

                                                                                                                       Advanced modelling techniques were
                                                                                                                       used to simulate all operating scenarios.
                                                                                                                       A subway environment simulation software
                                                                                                                       program was used for the 1D analysis of
                                                                                                                       the tunnel network, with computational
                                                                                                                       fluid dynamics used for the 3D analysis of
                                                                                                                       fire and smoke behaviour in complex station
                                                                                                                       geometries. A smaller, but statistically
10.                                                                                                                                                                      12.

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                                                                                                                                                13: At Gammel Strand, the adjacent
                                                                                                                                                waterway was kept open during
                                                                                                                                                construction by placing the worksite
                                                                                                                                                on a platform above the canal
                                                                                                                                                14: The abundance of natural light
                                                                                                                                                means using Cityringen does not feel
                                                                                                                                                like being underground

                                                                                                                                                During construction, groundwater was
                                                                                                                                                managed by a comprehensive re-infiltration
                                                                                                                                                system implemented and monitored closely,
                                                                                                                                                as groundwater is extracted for drinking in
                                                                                                                                                Copenhagen. Re-infiltration also ensured
                                                                                                                                                that the large number of historical buildings
                                                                                                                                                that are founded on wooden piles were not
                                                                                                                                                adversely affected by dewatering.

                                                                                                                                                In order to track building settlements
                                                                                                                                                unrelated to Cityringen, and for the
                                                                                                                                                seasonal fluctuations of heave and
                                                                                                                                                settlement in the ground to be recorded,
                                                                                                                                                initial baseline monitoring was carried
                                                                                                                                                out by Metroselskabet from 2009 onwards
                                                                                                                                                (three years before the contract was signed
                                                                                                                                                with the contractor) on a number of
13.                                                                                                                                             buildings along the Cityringen alignment.
                                                                                                                                                Furthermore, building condition surveys
corridor adjacent to the 19th-century marble     further working space at ground level,         relaunched to complete the drive from           of hundreds of buildings along the metro
church’s foundations.                            helping to limit the extent of the worksites   Nørrebroparken shaft to Øster Søgade            route were carried out both before and
                                                 and thereby reducing disruption to the         shaft in challenging soft and mixed             after construction.
At Gammel Strand, the station was partly         local community.                               ground conditions.
built under the canal. The waterway was                                                                                                         Arup’s reference design for the new metro
kept open for tourist boats during               Four earth pressure balance type tunnel        Monitoring                                      took into account the sensitivity of existing
construction, with the worksite placed on a      boring machines (TBMs) were used to            Implementation of an exhaustive risk            buildings and set out the framework for the
platform above the canal, allowing boats to      construct the twin tunnels (of 4.9m internal   management programme to monitor and             design and build contractor to carry out the
pass beneath.                                    diameter) to depths of between 20m and         minimise damage to third-party assets           works. During the design and construction
                                                 35m. Two TBMs bored the first parallel         and continuous monitoring of the ground,        phases, Arup was responsible for reviewing
The stations were generally constructed at a     drive, constructing the twin tunnels from      structures, groundwater, noise and vibration    and following up on the contractor’s
depth of approximately 19m below ground          the Nørrebroparken shaft to a shaft at         was critical to successful completion of        building damage assessments, including at
using cut-and-cover box structures. All bar      Sønder Boulevard. This drive was               the project.                                    Marmorkirken Station, the Magasin du Nord
one of the stations used a semi-bottom-up        predominantly through good quality hard                                                        department store building, and tunnel
method. In this method, the retaining walls      ground beneath residential areas. These        The Cityringen station footprints have          crossings under and above surface railways
and roof slab were constructed first, before     TBMs were then moved and relaunched for        been inserted into the existing urban fabric,   and existing underground metro tunnels.
excavating to the base level. Temporary          their second drive from Øster Søgade shaft     meaning that some station retaining walls       Alert and alarm values from the damage
props were placed between the station walls      to København H, passing through the heart      are only 1.5m from existing buildings,          assessments informed the monitoring plans
prior to the installation of the permanent       of the city close beneath many sensitive       including the foundations of the 260-year-      and the emergency plans.
floor slabs. Building the lid of the station     heritage structures. At the same time, two     old ‘Marble Church’. The new line
first reduced the level of noise during the      other TBMs bored, in twin tunnel formation,    connects with three existing railway            Detailed monitoring by both the contractor
excavation and construction of the lower         from the Control and Maintenance Centre        stations and two metro stations, so it was      and Metroselskabet took place during the
levels below the roof slabs. It also minimised   at Otto Buses Vej, underneath the main rail    also critical that the existing transport       works to confirm the assumptions for the
settlement of the neighbouring buildings.        corridor into Copenhagen to the shaft at       network was not compromised during              design models, and to record the impact
In addition, the roof slabs offered              Sønder Boulevard. They were then               construction works.                             of the construction works on existing

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                                                                                                                     15: The TBM passed very close to                                                                                                                    A further design challenge to tunnelling
                                                                                                                     the shallow foundations of the                                                                                                                      below Magasin du Nord was the complexity
                                                                                                                     Magasin du Nord department store                                                                                                                    of the department store’s structural system.
                                                                                                                     16: Kongens Nytorv Station was one                                                                                                                  It consists of multiple interconnected
                                                                                                                     of the most challenging locations,                                                                                                                  buildings constructed at different times, with
                                                                                                                     with mixed ground conditions, and                                                                                                                   different materials, on a range of foundation
                                                                                                                     nearby metro lines and shallow                                                                                                                      types. In addition, in 2000, the building’s
                                                                                                                     building foundations                                                                                                                                basement was lowered by approximately 1m
                                                                                                                                                                                                                                                                         to accommodate an additional shop floor
                                                                                                                                                                                                                                                                         and provide access from the original
                                                                                                                                                                                                                                                                         Kongens Nytorv metro station. There was a
                                                                                                                                                                                                                                                                         possibility that micro-piles used in that
                                                                                                                                                                                                                                                                         construction were still in place, with a risk
                                                                                                                                                                                                                                                                         that the TBM could hit these as it passed
                                                                                                                                                                                                                                                                         below the building.

                                                                                                                                                                                                                                                                         To reduce the building’s predicted
                                                                                                                                                                                                                                                                         settlement, and the risk of encountering
                                                                                                                                                                                                                                                                         the micro-piles, the contractor proposed
                                                                                                                                                                                                                                                                         lowering the new Kongens Nytorv Station
                                                                                                                                                                                                                                                                         and the Cityringen tunnel alignment to
                                                                                                                                                                                                                                                                         within 1.5m of the existing metro tunnels.
15.                                                                                                                                                                    17.                                                                                               A detailed analysis of the effect of the
                                                                                                                                                                                                                                                                         TBM passage on the existing metro
structures and infrastructure. More than                              data acquired. All site managers and           The settlement data and TBM parameters on         the existing metro tunnels with a clearance of   lifts, increased the excavation required and     tunnels was conducted to determine the
22,000 monitoring stations provided 200,000                           relevant members of the contractor’s           the database helped the contractor to tunnel in   only 1.5m, before diving, with very limited      would have led to higher costs.                  potential implications. The results showed
readings every day. Automated monitoring                              technical department, including TBM            difficult soil conditions. Monitoring data        clearance, beneath the shallow foundations of                                                     that the deflections and stress levels in the
occurred at variable frequency but often took                         technical staff, had full access to the        acquired during the project allowed for           several heritage buildings, including the        The contractor performed a detailed              existing metro tunnels were negligible and
place every 30 seconds when tunnelling was                            monitoring database and had specific duties    design optimisation and helped to avoid           flagship Magasin du Nord department store.       assessment at Kongens Nytorv, involving          could be accommodated by the tunnel
close to the monitoring points. Monitoring                            and roles regarding monitoring. A dedicated    unnecessarily costly and disruptive mitigation                                                     the analysis of a fully coupled 3D               structure. After crossing the tunnels, the
data fed into an extensive, real-time database.                       emergency action plan was continuously         measures in the centre of Copenhagen by           The risk of settlement and associated            geotechnical and structural model, with the      TBMs dived down at the maximum
                                                                      updated and in use during construction, with   allowing the contractor to precisely predict      damage to buildings and utilities in this area   advancement of the two TBMs modelled             allowable gradient (6%) to clear the
Both the contractor and client had dedicated                          precise procedures detailed in case any        the volume loss from TBM boring.                  would have been lessened if a deeper             ring by ring in order to identify all possible   underside of the Magasin du Nord
teams to manage the extensive quantity of                             threshold values were exceeded.                                                                  Cityringen station was constructed, with the     settlement scenarios. The initial analysis       foundations and any micro-piles that
                                                                                                                     Protecting heritage buildings                     TBMs passing beneath the existing metro          predicted that damage to the buildings           may still have been in place.
                                                                                                                     The contractor was required to carry out the      and through good soil conditions. However,       would be at unacceptable levels, so
                                                                                                                     works on the project without causing              this option would have significantly             additional mitigation measures needed            The contractor used both preventative
                                                                                                                     significant damage to third-party assets.         increased passenger time on escalators and       to be put in place.                              and corrective measures to mitigate the

                                                                                                                     Acceptable limits for typical building

                                                                                                                     damage were outlined within the contract –

                                                                                                                     damage should be limited to category 1

                                                                                                                     according to the classification in BRE

                                                                                                                     Digest 251, which defines damage as “fine

                                                                                        rin                          cracks which can be treated easily using

                 Zone with the highest risk                                                                          normal decoration. Damage generally

                      of settlement
                                                                                                                     restricted to internal wall finishes; cracks
                                                                                                                     rarely visible in external brickwork. Typical
                                                                                                                     crack widths up to 1mm”. Category 2
                                                                                                                     damage, where serviceability would be
                                                                                            Kongens Nytorv
                                                                                            Cityringen Station       affected – requiring external repointing of
                                                                                                                     brickwork and doors/windows needing
                                                                                                                     repair – with crack widths up to 5mm, was
                                                                                                                     not acceptable. Historical building archives
                                                                                                                     were used to provide information for the
                                                                                                                     assessment of building damage.                    17: The driverless metro trains run every
                                                                                                                                                                       three minutes at peak times, and every
                                                                                           Kongens Nytorv
                                                                                           Existing Station
                                                                                                                     Kongens Nytorv was one of the project’s           five minutes during the rest of the day
                                                                                                                     most challenging locations. In this area, the     18: The Øster Søgade shaft was used to
                                                                                                                     TBMs had to break out of the new station at       launch the TBMs and to incorporate
                                                                                                                     Kongens Nytorv, tunnel through shallow, soft      bifurcation structures for the metro
                                                                                                                     ground in mixed-face conditions, pass above       extension to Nordhavn
16.                                                                                                                                                                                                                     18.

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risk of damage to the buildings at Kongens       Transport network expansion                       bifurcation chamber was a tapered (in plan)
Nytorv. The preventative measures included       Arup is continuing to work on expanding           reinforced concrete shaft with stacked track
lowering the tunnel alignment as described       Copenhagen’s transport network to the north       bifurcation on the two lower structural levels,
above, filling disused underfloor heating        and south of the city. The Nordhavn branch        15m and 26m below ground level, and with a
conduits with lean concrete and using            of Cityringen, with two new stations, will        technical level housing equipment and plant
localised jet grouting to underpin sensitive     create a transport hub for the docklands          rooms approximately 7m below ground level.
foundations. Corrective measures included        redevelopment north of the city centre and
an extensive compensation grouting array         opened in March 2020. To the south-west,          For the larger crossover caverns where
and the preparation for emergency                Arup is working on the detailed design of the     tunnels branch off towards Nordhavn and
dewatering if required in order to allow         five-station underground extension to the         Sydhavn, Arup designed a novel, lightweight
access to the TBM face. A comprehensive          Sydhavn district. This is set for completion in   fire board panel system, supported by a steel
liquid levelling monitoring system was           2024, as part of the regeneration of the city’s   frame for the over-track exhaust duct in the
installed in the basements and ground floors     south harbour area. To ready the transport        ceiling. This replaced the heavy and
of the buildings most at risk of settlement,     network for these new elements, two               cumbersome fire-rated metal sheet work,
3D prisms and levelling bolts were installed     bifurcation structures were incorporated          traditionally used in other metros, saving time
on building façades and an automatic 3D          during Cityringen’s construction. This            and cost on the construction programme.
monitoring system was installed inside           required modification to the already planned
the existing metro tunnels to detect             Øster Søgade shaft and the introduction of a      Cityringen opened in September 2019.
tunnel convergence.                              new shaft at Havneholmen.                         Trains run every three minutes in the peak
                                                                                                   morning and evening commutes, and wait
The compensation grouting array consisted        The changes to the Øster Søgade shaft saw         times are less than five minutes during the
of 45 horizontal tube-a-manchettes ranging       the introduction of two additional tunnel         rest of the day. The line is forecast to
from 15m to more than 40m in length, with        interfaces to the western edge of the shaft.      transport up to 120 million passengers a
grout valves every 0.5m. Where the liquid        This was a complex project, as the worksite       year, with 85% of all Copenhagen residents
levelling systems indicated a localised          was also a tunnel construction service site for   now within 600m of a metro or train station.
foundation movement, the array enabled a         the TBMs creating the eastern part of             The new line is a fantastic example of
direct and immediate response with grout,        Cityringen between Øster Søgade and               elegant, efficient and intuitive rail design,
quickly re-establishing the foundation           København H. The design for the                   centred on delivering an effortless and            20.
stability. A maximum settlement of just          modification to the shaft minimised the           enjoyable travel experience for
1.2mm was measured during the passage of         disruption to the Cityringen works and            Copenhagen’s citizens and visitors, and
the first TBM, and a maximum value of            maximised future flexibility for the addition     building on the strengths of the city’s              Authors                                                Project credits                                   Kasper Kramer, Ben Kreukniet, Sachin Kumar,
0.8mm for the second, proving that the hard      of the Nordhavn branch to the metro network.      existing system. It proves that the                  Tony Evans was seconded into Metroselskabet’s          Client Metroselskabet I/S                         Maciej Kupczyk, Tatjana Lampe, Eduardo
work by Metroselskabet, the designers and        Crucially, the design also minimised any          architecture of rail systems can contribute          construction management team as Technical              Design and build contractor Copenhagen            Landete Mata, Jens Larsen, David Leal, Yu-Chen
the contractor had paid off. The best solution   unnecessary change that might impose              greatly to a city’s identity, with a sustainable     Manager during the project. He is an Associate         Metro Team (Salini-Impregilo, Tecnimont           Lee, Chris Lees, David Loosemore, Helle Lyng
                                                                                                                                                        Director in Arup’s Midlands Campus in the UK.          and Seli)                                         Svensson, Steve Macklin, Guy Macleod, Enrico
possible had been achieved for the station at    additional cost or disruption on the              design that can be maintained cost-
                                                                                                                                                                                                               Joint venture partners COWI, SYSTRA               Manganelli, Neil Martini, Stuart McClymont,
this location.                                   surrounding area. The Havneholmen                 effectively, long into the future.                                                                                                                            Jonathan McKiernan, Charles Milloy, Phil Morley,
                                                                                                                                                        Katrine Falbe-Hansen was seconded into                 Acoustics, architecture, civil engineering,
                                                                                                                                                        Metroselskabet and was responsible for building        construction management, electrical               Sabine Moser, Trent Murrihy, Omid Nakhaei, Paul
                                                                                                                                                        assessment coordination and third-party issues         engineering, façade engineering, fire             Newton, Anders Nohr, Alberto Palma, Dinesh
                                                                                                                                                        for Cityringen. She is a senior civil and structural   engineering, geotechnics, lighting design,        Patel, Aitana Paya Perez, Giuseppe Pelagalli,
                                                                                                                                                        engineer and is based in the Copenhagen office.        materials science, mechanical engineering,        Francesco Petrella, Saskia Polster, Gregory
                                                                                                                                                                                                               pedestrian modelling, programme and project       Quinn, Dirk Regenspurger, Mhairi Riddet, Derek
                                                                                                                                                        Neil Martini was the Project Manager. He was           management, structural engineering and            Roberts, Nina Rutz, Prakash Sabapathy, Russell
                                                                                                                                                        seconded into Metroselskabet as the tunnel             tunnel design Arup: Yakup Akkas, Jarrod Alston,   Saltmarsh, Sheela Sankaram, Cornelius
                                                                                                                                                        design manager during the project. He is an            Ambrogio Angotzi, Giulio Antonutto-Foi, Eva       Schneider, Nazaneen Shafaie, Ruth Shilston,
                                                                                                                                                        Associate in the Copenhagen office.                    Arquero, Mo Attia, Enrica Barzaghi, Andrés        Siegrid Siderius, Derek Smyth, Jamie Stern-
                                                                                                                                                                                                               Bascones, John Batchelor, Charles Betts, Johan    Gottfried, Colin Stewart, Igor Stipac, Louise
                                                                                                                                                        Nille Juul-Sorensen was the lead architect on          Beudeker, Joanna Bielecka, Paola Blasi, Andre     Stroud, Julia Summers, Matt Sykes, Sebastian
                                                                                                                                                        the project. He was also previously responsible        Blokker, Tamas Bodri, Lucio Boscolo Mezzopan,     Szafarczyk, Mohammad Tabarra, Rachel Taylor,
                                                                                                                                                        for the design of Copenhagen’s M1 and M2               Brendan Bradley, Nicholas Bruce, Edel Casserly,   Nick Troth, Rogier van der Heide, Alexandra van
                                                                                                                                                        metro lines. He is Arup’s global leader for            Tim Chan, Man-Yiu Cheuk, Francisco Cortes-        Tintelen, Jeroen Verwer, Ida Villumsen, Marie
                                                                                                                                                        architecture and a Principal in the Toronto office     Franco, Piotr Czapko, Andy Davidson, Fred         West Henriksen, David Whittles, Heather Wilson,
                                                                                                                                                        (he was formerly based in Copenhagen).                 Deacon, Tim Dixon, Jim Dunne, David Eborall,      Kristian Winther, Kevin Womack, Anna Wudzka,
                                                                                                                                                                                                               Anna-Maria Ejrup, Matthew Evans, Tony Evans,      Jan Wurm, Clara Yeung, Pietro Zanetti,
                                                                                                                                                        Mohammad Tabarra was responsible for                   Katrine Falbe-Hansen, Andrej Fojkar, Pernille     Gertraud Zwiens.
                                                                                                                                                        the tunnel and station ventilation design on           Fournais, Jens Frederiksen, Jens Fugl, Salome
                                                                                                                                                        the project. He is Arup’s global tunnel ventilation    Galjaard, Mads Gandil, Valentina Gastaldi, Tim    Image credits
                                                                                                                                                        lead and an Associate Director in the London office.   Goeckel, Rene Guenther, Na’amah Hagiladi,         1, 3, 4, 6–10, 14, 17, 20: Rasmus Hjortshøj –
                                                                                                   19: Compensation grouting was used                                                                          Stuart Hall, Diana Hare, Ali Hariri, Alexis       COAST
                                                                                                   to prevent the risk of excessive building            Kristian Winther was responsible for design            Harrison, Chris Harvey, Des Hendrick, Michael     2, 5, 11, 12, 16, 19: Arup
                                                                                                   movement                                             and coordination of the main concept for the           Hess, Daniel Hof, Tom Honnywill, Andrew           13, 18: Dragør Luftfoto/Metroselskabet I/S
                                                                                                   20: Cityringen opened in September 2019;             station architecture. He is an Associate in the        Jenkins, Aslak Jensen, Inge Jensen, Nille         15: Arup/Metroselskabet I/S
                                                                                                   some 85% of Copenhagen residents are                 Copenhagen office.                                     Juul-Sorensen, Tomasz Kasprus, Areti Kavoura,
                                                                                                   now within 600m of a metro or train station

14                                                                                                                                                                                                                                                                          1/2020    |   The Arup Journal          15
The Arup Journal Issue 1 2020

                                                                  Digging deep
                                                                  Creating a five-level basement below a fully operational
                                                                  five-star hotel in London’s Mayfair
                                                                  Authors Alice Blair, Sarah Glover, Dinesh Patel and Andy Pye

                                                                  The owners of Claridge’s, a five-star            The project was put on hold following the
                                                                  hotel in the heart of London’s exclusive         2008 global financial crisis. When the client
                                                                  Mayfair district, wanted to enhance the          revisited the idea in late 2015, they had even
                                                                  services offered to their guests and             more ambitious plans – they now wanted to
                                                                  increase capacity. To do so, they needed         develop a five-level basement. Having
                                                                  to expand the hotel. Planning reasons            successfully collaborated on projects
                                                                  meant they could not increase the height         previously, Arup and the design and build
                                                                  of the building, so an alternative solution      contractor, McGee, worked together on a
                                                                  was needed. Could a modern extension             methodology to excavate and construct the
                                                                  be created by excavating below the               basement using mining techniques.
                                                                  building – without disrupting the hotel
                                                                  services or disturbing the guests?               This was a uniquely challenging project, as it
                                                                                                                   required the design and construction of a
                                                                  In 2007, when the Maybourne Hotel Group          22m-deep basement and 30m-deep foundations
                                                                  initially proposed extending Claridge’s by       beneath a 90-year-old concrete raft slab
                                                                  constructing two basement levels below the       founded on material that was difficult to safely
                                                                  Grade II-listed building, they were advised      excavate. Adding to the complexity, in order to
                                                                  that the hotel could not remain open during      avoid disruption to hotel guests, all
                                                                  the works. But closing Claridge’s temporarily    construction materials, machinery and
                                                                  was not acceptable to the owners. A closure      excavated spoil needed to pass through a single
                                                                  of any kind would jeopardise client loyalty –    2m x 2m window to the rear of the hotel. The
                                                                  the hotel has long boasted an impressive         construction operation was performed from a
                                                                  guestlist that includes Hollywood celebrities,   single 7m2 room, which was the only available
                                                                  rock stars and royalty. The owners required a    space that the client could afford to give to the
                                                                  solution in which facilities could be upgraded   construction team; later, a second room was
                                                                  while the hotel remained fully operational.      provided at the front of the building.

                                    1: The five-storey basement
                                    was constructed under the
                                    1920s Art Deco section of
                                    the hotel
                                    2: All the machinery and
                                    excavated materials passed
                                    through a single window to
                                    the rear of the hotel
1.                                                                2.

16                                                                                                                           1/2020   |   The Arup Journal       17
The Arup Journal Issue 1 2020
CLARIDGE’S HOTEL                      |   LONDON, UK

                                                                                                               The design team developed a solution that          excavation electrically operated to minimise
                                                                                                               involved coring through the existing               noise, vibration and possible pollution.
                                                                                                               basement raft slab in a single 2m x 2m

                                                                                                               location, and from there constructing              This work required close collaboration
                                                                                                               horizontal tunnels (more than 400m in total)       between Arup, McGee and temporary works
                                                                                                               under the slab to below each of the                designer RKD, with Arup carrying out

                                                                                                               61 columns requiring support, with four            extensive analysis of the existing building
                                                                                                               additional columns supported on new transfer       foundations to understand the load path from
                                                                                                               structures. Vertical shafts 1.8m in diameter       the building and determine its response

                                                                                                               were then hand-dug beneath each of the             through all phases of the work. Movement
                                                                                                               columns. These needed support to depths of         had to be limited, as excessive displacements
                                                                                                               30m in order to form caisson foundations. A        would have had serious consequences for the

                                                                                                               five-storey reinforced concrete column was         structure, sensitive listed heritage features
                                                                                                               built within each shaft up to the underside of     and – most importantly – the hotel occupants.
                                                                                                               the existing raft to provide vertical support to   A rigorous regime of movement monitoring

                                                                                                               the superstructure above. Once complete, the       and control was put in place during

                                                                                                               basement area was excavated around the new         construction. Buildability drove the design;
                                                                                                               columns to create the basement space. All          the work needed to be methodically planned,

                                                                                                               25,000m3 of excavated material was removed         as construction was taking place in such a









                                                                                                               through the one window at the rear of the          confined space and with access to the



                                                                                                               building, with all equipment used in the           construction site so limited.

                                                                                                                                                                  Raft slab investigation
      3: More than 400m of horizontal tunnels were
                                                                                                                                                                  Claridge’s first opened in 1856 and, before the    6.
      constructed in total
                                                                                                                                                                  basement extension began, it was made up of
      4: The shafts were hand-dug, with temporary steel                                                                                                           two buildings – a Victorian-era seven-storey       response to the movements from the                crack pattern and associated concrete
      liners installed by the miners
                                                                                                                                                                  building constructed in the 1890s and an Art       proposed construction methodology.                deflections at rupture. This combined analysis
      5: Basement level one was excavated directly                                                                                                                Deco building at the east of the site dating                                                         confirmed that the slab behaviour would
      below the 1920s raft slab                                                                                                                                   from the 1920s. The Victorian building was         An 800mm x 800mm section was cored                remain acceptable, provided any deflections
      6: 3D model showing the foundations and                                                                                                                     constructed with load-bearing masonry walls        out to investigate the slab’s concrete            caused by excavation underneath were
      columns, along with the first basement level                                                                                                                founded on an unreinforced mass concrete           strength and reinforcement quantity. This         carefully controlled.
                                                                                                                                                                  slab, making it unsuitable to excavate under.      section was lightly reinforced, matching
                                                                                                                                                                                                                     minimum code requirements at the time of its      Challenging ground conditions
                                                                                                                                                                  The Art Deco section consists of a nine-           construction. As access restrictions prevented    While the raft slab was being examined, a
      Pioneering solution                                                                                                                                         storey steel frame with heavy perimeter            investigations elsewhere, it was not possible     significant geotechnical issue was being
      The client’s aim was to create 5,500m2 of                                                                                                                   load-bearing walls founded on a 50m x              to confirm whether any other areas of the raft    investigated, one that had the potential to stop
      extra space. The upper two floors of the                                                                                                                    25m x 1.1m deep concrete slab. With careful        had more reinforcement than this sample.          the project. Claridge’s is located in the former
      basement were earmarked for a range of new                                                                                                                  construction of a new supporting foundation                                                          course of the River Tyburn, and initial site
      offerings for hotel guests, including a gym,                                                                                                                system, this load-bearing raft slab could be       Using only the minimum 1920s code                 investigations suggested that the raft was
      a spa and two swimming pools. The three                                                                                                                     converted into a suspended slab, thereby           reinforcement as a conservative estimate,         founded on combination sand and gravel
      lower levels were to be used for back-of-                                                                                                                   allowing the basement to be excavated below        Arup carried out extensive analysis of the raft   material. After further analysis, it was
      house facilities and plant. By moving some of                      4.                                                                                       the slab. In order for this plan to be feasible,   strength to inform the design and understand      determined that the raft slab was bearing on
      the staff areas into the basement, this freed up                                                                                                            it was crucial to understand how the slab          the construction-related movements that the       an alluvial clay silt deposit of varying depth
      space at lower ground floor level, which could                                                                                                              would behave at all stages of construction.        building would experience. Deflections and        (up to 2m) on layers of gravel above London
      then be used for luxury retail units instead.                                                                                                                                                                  settlements were analysed with soil-structure     Clay. In situ, the alluvial layer has high-
      Relocating the roof-level mechanical and                                                                                                                    Arup needed to quantify the strength of the        2D and 3D finite element (FE) analyses. The       bearing pressure, but it is very sensitive to
      electrical plant areas to the basement would                                                                                                                slab and determine the density of                  staged geotechnical analysis modelled the         moisture. The stability of this soil layer
      create the space for 40 new rooms, including                                                                                                                reinforcement within it to ensure it could         various activities across the complete            during excavation was a huge safety concern,
      penthouse accommodation on the top floor.                                                                                                                   span over the tunnelling works and safely          construction sequence to predict the load         as once disturbed and in contact with water it
                                                                                                                                                                  transfer loads both during the tunnelling          distribution in the slab, along with ground       turns into a paste-like consistency, making it
      Arup’s geotechnical, structural and advanced                                                                                                                operations and when the new columns were           settlement and heave.                             impossible to tunnel safely through and
      technology engineering teams worked closely                                                                                                                 in place. There was limited information on                                                           risking excessive building settlements.
      with McGee to minimise the significant ground                                                                                                               the slab – one of the only sources was a           A separate 3D FE analysis investigated
      and structural risks inherent in constructing a                                                                                                             November 1931 article on construction of           inelastic cracked behaviour of the raft and       A solution needed to be found to prevent this
      basement under a heritage building. They                                                                                                                    the Art Deco wing in The Builder magazine,         failure mechanisms, using a Continuous            sensitive soft layer from turning into liquid
      initially spent six months carrying out site                                                                                                                which noted the overall quantity of                Surface Cap Model for the concrete material       during the mining operation. Options
      trials, material tests, and geotechnical and                                                                                                                reinforcement, as well as the difficult soil       model that included each element of               considered included ground freezing and
      structural analysis to demonstrate that the                                                                                                                 conditions. The slab is an early example of        reinforcement. Hand calculations and              grouting. However, ground freezing would
      proposed basement construction methodology                                                                                                                  the use of a reinforced raft. As it did not meet   non-linear FE analysis were also carried out,     have required extensive additional access
      was workable. There was no precedent for                                                                                                                    modern codes of practice, one of the major         with Arup’s Advanced Digital Engineering          within the hotel, and there was also the
      such an ambitious project.                                                                                                                                  challenges was understanding the raft’s            team modelling the concrete to analyse the        potential that this method would cause soil

      18                                                                                                                                                                                                                                                                        1/2020    |   The Arup Journal      19
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    A                                                              C


                                                                                                                                                            A1                   A                 B                  C            D          E                    F                          G                                 H                                                 J     K                    L                                               M                          N                   0   CL                        p

                                                                                                     7: 152 UC steelwork sections were used to frame         1                                                                               Existing
CLARIDGE’S HOTEL                            |   LONDON, UK
                        I                         J                                K                          L                         M                                N


                                                                                                                                                                                                                                                                    25/05/2017 17:09:34
                                                                                                                                                     Existing column centre-point
                                                                                                                                                                                           1. This drawing is to be read in conjunction with all
                                                                                                                                                     Assumed line of existing raft above   relevant design reports, specifications, architectural
                                                                                                    4                       4.1                                                            and services drawings, specialist sub-contractor’s
                                                                                                                                                                                           drawings including approved builders work drawings
                            Avoiding having to1600dp
                                                 fix xreinforcement
                                                        600mm                                                 1325
                                                                                                                                                                                           and other contract documents.                                                                  all carried out at night, with the excavated                                                                                16: Two service shafts
                            prevented any delayTransfer
                                                  thatbeammight have caused
                                                                      CL Transfer beam                                                                                                     2. For general notes drawing refer to drawing
                                                                                                                                                                                           CH-AR-DGE-XXX-S-0100.                                                                          material removed in wheelbarrows through                                                                                    were constructed
                            softening of the base of the foundation.                                                                  Assumed step in
                                                                                                                                                                                           3. For internal and perimeter column head details                                              the hotel corridors. The 4m diameter vertical                                                                               under the hotel’s
                                                                                                                                                                                                                                                                                          shafts were built first, with the 3m diameter
                                                              6                                                                                                                            refer to drawings CH-AR-DDE-XXX-S-4401 and
                                                                                                                                      soffit of existing
                                                                                                                                      raft above
                                                                                                                                                                                           CH-AR-DDE-XXX-S-4411.                                                                                                                                                                                                      Victorian wing to
                       Concrete columns                                           1200
                                                                                                                                                            4. For caisson pile information refer to drawing
                                                                                                                                                                                                                                                                                          horizontal tunnels then constructed from the                                                                                provide building
                       Reinforced concrete pads (each measuring 335          265       335   265                                                                                                                                                                                          basement to reach the shafts. These shafts,                                                                                 services routes to
                                                                                                                                                            5. For lining wall tolerances refer to General
                                                                                                                                                                                                                                                                                                                                                                                                                      the basement
                       1.6m x 1.6m, and 1.2m in depth) were                                                                                                 Arrangement drawings.
                                                                                                                                                                                                                                                                                          tunnels and connection chambers were as
                       constructed on top of the concrete infilled                                                                                                                                                                                                                        logistically challenging as the main basement.                                                                              17: Claridge’s

                       caissons. Internal columns 600mm in65                                                                                                                                                                                                                                                                                                                                                          remained fully

+16.070 m (Indicative)
                       diameter were then built to the underside of                                                                                                                                                                                                                       Movement monitoring and control

                                                                                                                                                                                                                                                                                                                                                                                                                      throughout the
                       the raft from inside the 1.8m diameter shafts.                                                                                                                                                                                                                     During construction, extensive movement                                                                                     basement extension,

                       This column diameter was the largest that                                        391                                                                                                                                                                               monitoring of the building took place.                                                                                      with guests barely
                       could be accommodated within the shafts                                                                         A                                                                                                                                                  Monitoring mechanisms were installed to

                                                                                                                                                                                                                                                                                                                                                                                                                      noticing the works
                       while still allowing safe access for                                                                  Void TBC
                                                                                                                                                                                                                                                                                          assess movement of the existing raft and the                                                                                taking place
                       construction. The column reinforcement was                                                                                                                                                                                                                         building overall. Real-time movement                                                                                        beneath them
                       made up of 2m lengths with coupler                                                                                                                                                                                                                                 monitoring was put in place on all columns,
Transfer beam. Beam connections, making the reinforcement easier                                                                                                                                                                                                                          inclinometers were placed internally on all
1600dp x 600mm

TOC to suit adit frame
                       and safer to handle and reducing rebar                                       13.                                                                                                                                                                                   retaining walls, and precise level studs and
                       congestion in the column. The couplers were                                                                                                                                                                                                                        3D targets were positioned externally. Liquid
                       placed at waist height to enable the                                         columns
                                                                                                          existing in   thispilesmanner freed up space in the
                                                                                                          Assumed location of
                                                                                                                   contiguous                                                    basement level was fully excavated, it created                                                           levelling sensors enabled movements to be
600Ø R.C column
                       reinforcement to be fixed more             readily.
                                                            3 1 : 20        - Profile      A        excavated         basement        at each     column location.               space to construct a 750mm diameter,                                                                     displayed in the site office in real time.         17.
                       Self-compacting C60/75N concrete                       was used              Using a 1.2m diameter column also provided                                   19m-deep contiguous pile wall around the
          SSL +10.400 min each column, ensuring good quality                                        sufficient space during construction for                                     basement perimeter. A modified electrically                                                              The hydraulic fluid-filled flat jacks at the top   extensive technical knowledge, skills and
             Level B1
                       concrete in zones of congested reinforcement            4                    workers      4.1
                                                                                                                  to   fix    the   column    reinforcement                      powered piling rig was used for this work to                                                             of the columns allowed for the control of raft     experience to overcome the significant          Authors

                       and avoiding the need to use a vibrating                                     from within the steel reinforcement cage.                                    avoid diesel fumes and reduce noise. The rest                                                            movements (ground settlement and heave)            challenges in creating a five-storey basement   Alice Blair led the structural design delivery
                       poker to 1200Ø
                                  compact          the concrete 335
                                        nominal diameter
                                                                in the265small   1200
                                                                                                                                                                                 of the basement was excavated and built                                                                  and for adjusting the distribution of loads        below this Grade II-listed building.            on the project. She is an Associate in the
                                 for R.C detailing                                     335   265
                                                                                                                                                                                                                                                                                                                                                                                             London office.
                       access shafts. Steel shutters were used for the                              All the columns were cast to the underside of using traditional top-down construction, with                                                                                           going into the new columns. The
                       formwork to provide a high-quality concrete                                  the existing raft. The column heads were cast each basement level taking two months to                                                                                                measurement systems allowed for the actual         With construction taking place beneath an

                                                                                                                                                                                                                                                                                                                                                                                             Sarah Glover was the Project Manager. She
                       finish, with the added advantage that they                                   with twin hydraulic jacks installed on top of                                excavate and construct.                                                                                  loads from the superstructure to be                operational hotel, in such confined space       is a geotechnical engineer and Associate
                       could be reused across the site during                                       them   and      beneath         the raft.  These  were to                                                                                                                             determined. These confirmed that the actual        and with such limited site access, the

                                                                                                                                                                                                                                                                                                                                                                                             Director in the London office.

                       construction. To prevent buckling,         di
                                                                            temporary               engage the column, so they could take the                                    Service shafts below Victorian wing                                                                      building loads were within design tolerance.       design process was governed by what


                       struts were used to stabilise the columns                        in          superstructure load from above and control                                   Two service tunnels were constructed                                                                     At the end of construction, the hydraulic          could be practically and safely built.

                                                                                                                                                                                                                                                                                                                                                                                             Dinesh Patel was the Project Director. He is
                       the 22m-deep shaft until the basement floors                                 raft movement.                                    A                          underneath the Victorian section of the hotel                                                            fluid was replaced with cement grout,              Each element of construction required           a geotechnical engineer and Director in the
                       were built.                                                                                                          Void TBC                             to provide building services routes into the                                                             locking the building into its final position.      meticulous planning. The £37m basement          London office.
                                                                                                    The tunnelling works, shaft excavation and                                   basement, along with a lift and stair core. The                                                                                                             works were delivered on budget, four
                       The columns at the edge of the building form construction of the columns took 18 months.                                                                  new access core serves the first three                                                                   Building the impossible basement                   months ahead of programme and carried           Andy Pye was lead structural engineer on the
                                                                                                                                                                                                                                                                                                                                                                                             project. He is an Associate Director in the
                       part of the retaining wall and are subjected to Once all the columns were built and                                                                       basement levels, providing a shorter route for                                                           The successful completion of this project          out while the hotel remained fully
                                                                                                                                                                                                                                                                                                                                                                                             London office.
                       eccentric loads from above. These columns                                    preloaded, the tunnel steelwork could be C2 25/05/17hotel                          DT guests   AB      and
                                                                                                                                                                                                             AB staff into the new facilities.                                            would not have been possible without close         operational at all times, with guests
                       are 1.2m in diameter and located to one side                                 carefully dismantled and the ground beneath                Revised as Clouded
                                                                                                                                                               C1        30/01/17
                                                                                                                                                                                 The   DT
                                                                                                                                                                                          tunnels  AB
                                                                                                                                                                                                                 built to provide services                                                collaboration between McGee, Arup and              oblivious to the feat of engineering that       Project credits
 ill void as           of the 1.8m-wide shafts. Offsetting the edge                                 the existing         raft
                                                                                                          Assumed location  of removed. When the first Construction Issue        access to the lowest level. These works were                                                             RKD, which collectively drew on their              was going on below their feet.                  Client Maybourne Hotel Group
quired to suit                                                                                                        existing contiguous piles                                                   Rev         Date         By          Chkd         Appd
ep in soffit                                                                                                                                                                                                                                                                                                                                                                                 Norman McKibbin – Director of Construction
                                                                                                                                                                                                                                                                                                                                                                                             Design and build contractor McGee
                                                                                                                                                                                           13: Twin hydraulic
                                                                                                                                                                                                                                                                                                                                                                                             Jim Mackey – Project Director
                                                                                                                                                                                           jacks sit atop each                                                                                                                                 Awards                                        Temporary works designer RKD Consultant
                                                                                                                                                                                           column, to transfer the
                                      1800Ø construction                                                                                                                                   13 Fitzroy Street                                                                                                                                                                                 Geotechnical engineering, tunnelling,
                                      shaft (indicative)
                                                                                                    4                       4.1                                                            load and help control
                                                                                                                                                                                           London W1T 4BQ
                                                                                                                                                                                                                                                                                                                                               Council on Tall Buildings and
 00dp x 600mm
ansfer beam. Beam
                                                                                                                                                                                           Tel +44(0)20 7636 1531 Fax +44(0)20 7580 3924
                                                                                                                                                                                                                                                                                                                                                                                             hydrogeology, structural engineering and
                                                                                                                                                                                           raft movement
OC to suit adit frame                                                                                         1325                                                                         Client
                                                                                                                                                                                                                                                                                                                                               Urban Habitat                                 BIM Arup: Paul Bailie, Samila Bandara, Alice
                                      1200Ø nominal diameter
                                      for R.C. detailing                                                                                                                                   McGee Group
                                                                                                                                                                                           14: The edgeHoldings LTD.
                                                                                                                                                                                                          columns                                                                                                                              Geotechnical Engineering Award of             Blair, Chris Brewis, Tristan Ferguson, Orlando
                                                                                                                                                                                           form part of the                                                                                                                                    Excellence (2020)                             Gibbons, Rupert Gibson, Sarah Glover,
                                                                                                                                                                                           retaining wall                                                                                                                                                                                    Rosemary Judd, Marialina Klokidi, Doreen
                                                                                                                                                                                           15: The Basement
                                                                                                                                                                                           Project Title
                                                                                                                                                                                                      internal columns                                                                                                                         Concrete Society Awards 2019                  Lu, Frank O’Leary, Dinesh Patel, Anton Pillai,
                                                                                                                                                                                           measured 600mm in                                                                                                                                   Highly Commended                              Barrie Porter, Andy Pye, Darryl Tanner, Bryen

                                                                                                                                                                                           diameter – the largest                                                                                                                                                                            Vieira Commins, Dunshun Yang.
                                                                                                                                                                                           possible size that would                                                                                                                            Ground Engineering Awards 2019
                                                                                           9   00                                             0
                                                                                                                                                                                                                                                                                                                                               Editor’s Choice
                                                                                                                                                                                           Drawing Title
                                                                                        us                                              ø
                                                                                                                                                                                           still allow  safeand Details                                                                                                                                                                      Image credits

                                                                                  Ra                                                                                                       Column   Sections

                                                                                                                                                                                           Column   A4, B4 and
                                                                                                                                                                                           construction        Adjacent
                                                                                                                                                                                                             access                                                                                                                                                                          1, 6, 11, 14, 15: Arup

                                                                                                                                                                                           Transfer Beam                                                                                                                                       UK project with a geotechnical value over     2, 8, 9, 13, 16, 17: Paul Carstairs/Arup
                                                                                                                                                                               A                                                                                                                                                               £3 million: Highly Commended                  3: McGee
                                                                                                                                                                                           Scale at A1
                                                                                                                                                                                                           As indicated
                                                                                                                                                                                                                                                                                                                                                                                             4, 12: Nick Carter
                                                                                                                                                                                                                                                                                                                                               British Geotechnical Association              5, 7: Daniel Imade/Arup
                                                                                                                                                                                           Arup Job No
                                                                                                                                                                                                                                                                                                                                               Fleming Award (2018)                          10: RKD Consultant
                                                                                                                                                                                           245269                                             C2

                            14.                                                                                                                                                            CH-AR-DSE-XXX-S-4554                                                     15.                   16.
                                                                                                                                                                                                                                                           © Arup

                            22                                                                                                                                                                                                                                                                                                                                                                       1/2020     |   The Arup Journal          23

Taking flight
Beijing Daxing is the largest airport in the world and acts as
a new gateway for the Chinese capital
Authors Robert Feteanu, Ming Li, Fangzhou Su, Kelvin Wong and Vala Yu

The spectacular starfish-shaped Beijing          Fire safety design
Daxing International Airport is one of the       The airport’s vast size, the high footfall and
biggest single-structure terminals in the        the terminal’s flowing interconnected form
world, measuring 1.2km from end to end.          present a significant number of design
Covering more than 700,000m2, it is the          challenges, particularly in relation to the fire
largest airport (in terms of size) globally.     strategy. At the heart of the airport, there is a
It opened in September 2019 and                  single 500,000m2 central space, spanning
currently handles 300 take-offs and              from the fourth floor to two levels below
landings an hour and 42 million                  ground – this is one of the largest unseparated
passengers per year. This will eventually        fire compartments in the world.
grow to 100 million passengers annually.
                                                 The eight-platform transportation hub below
Working closely with Beijing Institute of        the airport makes travel to and from the
Architectural Design, Arup designed a            terminal convenient for passengers, but from
number of innovative solutions for this          a fire safety point of view adds further
project. The firm provided fire engineering,     complexity, as the space for emergency
passenger and logistics simulations and          discharge of occupants to the outside is
structural peer review services. This work has   limited. Arup took the lead in providing the
resulted in significant material and cost        fire safety design solutions and coordinating
savings, and carbon emission reduction.          with the various clients, operators and
Successfully integrating the ground              approval authorities in order that a consistent
transportation centre with the terminal          fire design, agreed on by all stakeholders, was
building, for instance, has helped to save at    approved. The firm overcame these
least 1.6 million hours for nearly 30 million    challenges by deploying an innovative
passengers every year.                           performance-based fire design strategy.

                                                                           1: The transportation
                                                                           hub beneath the
                                                                           airport provides
                                                                           access to high-speed
                                                                           rail, intercity trains and
                                                                           the airport express
                                                                           2: The airport is
                                                                           arranged around a
                                                                           large central space
                                                                           and measures 1.2km
                                                                           from end to end

1.                                                                                                      2.

24                                                                                                           1/2020   |   The Arup Journal   25

There were four main aspects to this strategy:                                                                                3: Depending on            diluted by the sheer volume of the atrium                                                                                       6: The building’s
• means of escape;                                                                                                            the location of a fire,    space and then removed through the vents.                                                                                       design means that
• smoke extraction;                                                                                                           there are various                                                                                                                                          smoke is directed
                                                                                                                              egress stairs and                                                                                                                                          upwards; the huge
• interface with the railways; and                                                                                                                       Arup conducted simulations to ensure the
                                                                                                                              exit strategies                                                                                                                                            central atrium space
• fire protection for the roof.                                                                                                                          design was optimised for smoke extraction                                                                                       at the airport’s heart
                                                                                                                              4: The airport is          and that people would be able to escape.
                                                                                                                              divided into six                                                                                                                                           allows smoke to be
Means of escape                                                                                                                                          These tested what would happen if some                                                                                          diluted naturally
                                                                                                                              smoke control zones
Arup divided the airport’s public space into                                                                                                             vents failed to open or if smoke rose high                                                                                      7: MassMotion helped
30 zones, each spanning between 2,000m²                                                                                       5: Arup used several       into the ceiling, stratified, spread out, or
                                                                                                                              techniques to prevent                                                                                                                                      to size and locate the
and 48,000m². Rather than a conventional                                                                                                                 lost its drifting power because of the heat.                                                                                    vertical circulation
                                                                                                                              fire from spreading
solution of zones separated by solid walls, a                                                                                 from one zone to
                                                                                                                                                         The results of these simulations were then                                                                                      elements such as lifts
mix of flexible shutters and doors were used                                                                                  another, including fire    used to refine the placement of vents and                                                                                       and escalators
so that the spread of fire and smoke could be                                                                                 separation boards and      other measures. Arup also developed
contained and safe spaces created without                                                                                     passive vents in the       augmented reality tools to visualise the
affecting passenger circulation during normal                                                                                 roof and downstands        smoke simulation.
operational times. The higher risk areas with
high fire load were, however, constructed for                                                                                                            Interface with the railways
full fire containment. These were limited to a                                                                                                           Below the airport terminal is the 80,000m²
maximum area of 2,000m² and equipped with                                                                                                                underground transportation hub for high-
two-hour fire-rated construction elements and                                                                                                            speed rail, intercity trains and the airport
1.5-hour fire-rated floors.                                                                                                                              express to Beijing city. There are three
                                                                                                                                                         underground stations, eight platforms and
In the event of a fire, people can leave the                                                                                                             16 tracks for five railway lines. The platforms    6.
zone where there is an immediate threat and                                                                                                              are located on basement level two and the
take shelter in a safe space nearby. The                                                                                                                 concourses on basement level one.                  roof trusses within a 6m to 9m distance above      The detailed passenger flow outputs from the
decision can then be taken to either evacuate                                                                                                                                                               the floor needed to be fire protected. The         simulation tools enabled Arup to demonstrate
occupants further if the fire escalates or allow                                                                                                         Arup liaised with both the railway and airport     majority of the roof structure did not require     the effects of suggested design modifications
them to return to the area if it is safe to do so.   3.                                                                                                  authorities to develop a strategy. Normally,       additional protection, as its height meant that    at a stage in the project when they were
                                                                                                                                                         fire safety plans in such cases are developed      it would be sufficiently far from any ground-      relatively inexpensive to implement.
There are 11 escape staircases in the large          Smoke extraction                                    activity resumes. Arup needed to consider       separately, but given the interdependency          level fire. This finding led to a cost saving of
central area; these shorten the escape distance      The second element of the fire safety strategy      comfort and operational continuity as a major   between the two in this case, that approach        several million renminbi.                          Every aspect of the airport has been designed
to the building perimeter. Arup provided             was smoke extraction. This is vital to              part of its strategy.                           was not practical.                                                                                    around passenger experience, which includes
different exit strategies for the central zone       minimise the risk to building occupants and                                                                                                            Terminal simulation and analysis                   the provision of passenger processing
based on the fire location. If a fire is detected    reduce potential damage to the building.            The terminal was divided into six smoke         Arup developed a proposal that was accepted        Beijing Daxing is expected to handle up            facilities and sizing of corridors to prevent
on the ground floor, for example, the egress         China’s building codes assume much smaller          control zones – the central zone and five       by the airport and railway approval                to 72 million passengers by 2025. Arup             excessive passenger congestion. Passenger
stairs in the central area will be closed and        rooms than those present in Beijing Daxing.         piers. Downstands were installed within         authorities as well as the national fire expert    used a series of simulation tools that             processing facilities include boarding gates,
occupants on other floors in the building will       Because of the airport’s vast open space,           the perforated ceilings to prevent smoke        review meetings. The firm proposed using           combined airport schedules and passenger           aircraft stands, check-in counters, bag drop
be directed by smart signage towards egress          smoke could potentially fill a larger area          spreading from one zone to another, so          the transportation interchange hall that           flow data to optimise the airport’s design         areas, security checkpoints, passenger
stairs along the building perimeter. Should a        without being obstructed. The smoke                 that if a fire occurs in one pier, the other    connects the railway areas and the terminal        so that it can accommodate both the current        holdrooms, inbound and outbound border
fire be detected on other floors, then all stairs    extraction is directed at both helping people       four can remain operational. To extract         as a main circulation space. This hall is          and expected number of passengers. This was        control, bag reclaim and washrooms.
are made available to allow rapid evacuation         escape and preventing smoke spreading and           smoke from the building, Arup made full         designed as a safe area. It has features such as   the first time an airport in China was fully
of people close to the fire. Arup performed          affecting other areas of the building. It is rare   use of the roof, incorporating passive vents    an opening towards the roof, sufficient means      simulated before construction and also the         Passenger flows were particularly
simulations for both scenarios to make sure          that an airport needs to be fully evacuated         between its metal and glass elements.           of escape to the outdoors and no high fire         first project on which Arup integrated these       complicated. Most international airports
they were acceptable and in order to gain the        during a fire; more often, the fire is localised,   The building was designed so that smoke         load use, such as retail areas or fuel storage.    two types of data and two different software       have departure and arrival areas split across
approval of the expert panel.                        people move away from it and normal                 is directed upwards; that way, it can be        This significantly reduces the required            packages, Simio and Oasys MassMotion.              different floors, but Beijing Daxing takes
                                                                                                                                                         number of egress stairs directly extending                                                            this even further, with domestic and
                                                                                                                                                         from the concourse level to the ground. It                                                            international flights occupying separate
                                                                                                                                                         also means that during an evacuation,                                                                 floors. The main passenger flow therefore
                                                                                                                                                         passengers can remain in a familiar,                                                                  spans over four floor slabs. In addition, a
                                                                                                                                                         comfortable environment.                                                                              separate check-in and security screening
                                                                                                                                                                                                                                                               area in the basement is planned; this will
                                                                                                                                                         Fire-proofing the roof                                                                                serve flights at the proposed satellite building,
                                                                                                                                                         Finally, the fire safety engineers had to                                                             which will be located away from the main
                                                                                                                                                         consider the large-scale steel-framed roof                                                            terminal. All passenger flows needed to be
                                                                                                                                                         structure. Under China’s building code, steel                                                         connected to the roadways and the ground
                                                                                                                                                         structures need to be protected by fire-proof                                                         transportation centre. This meant that the
                                                                                                                                                         paint to make sure they achieve the required                                                          analysis had to incorporate a complex set
                                                                                                                                                         level of fire resistance. Arup’s performance-                                                         of vertical circulation demands spanning
                                                                                                                                                         based model looked at the worst-case fire                                                             six floors in order to identify potential
                                                                                                                                                         scenarios and analysed their impact on the                                                            bottlenecks at different times of the day
                                                                                                                                                         roof structure. The results showed that only                                                          based on flight arrivals and departures.
4.                                                   5.                                                                                                                                                     7.

26                                                                                                                                                                                                                                                                      1/2020    |   The Arup Journal            27
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